The present invention relates to a parking brake apparatus for industrial vehicles.
Like ordinary automobiles, industrial vehicles, such as forklifts, have a service brake and a parking brake. The service brake is used for controlling speed when the vehicle is moving and for stopping the vehicle. The parking brake is for maintaining the vehicle in a stationary position when the vehicle engine is not in gear. The parking brake is connected to a parking lever by a cable or a link. The parking lever is manipulated by a hand or a foot. A manipulation force applied to the lever is transmitted to the parking brake by the cable or the link.
Japanese Unexamined Patent Publication No. 6-247190 discloses an industrial vehicle having an auxiliary brake. The vehicle has a transmission, which includes a torque converter and hydraulic forward and reverse clutches. The auxiliary brake is located in the transmission. When the vehicle is moving and handling a load at the same time, the handling speed of the load is controlled based on the manipulation amount of a loading lever. Specifically, the engine throttle is controlled by manipulating the loading lever. The load manipulation speed is controlled based on the engine throttle. The vehicle speed is set to a target value regardless of the engine speed. The target value of the vehicle speed is determined based on the depression amount of an acceleration pedal. That is, the braking force of the auxiliary brake and the engagement of one of the forward and backward clutches are controlled such that the vehicle speed matches the target value.
The parking brake is switched between a parking position and a release position by manipulating a parking brake lever. The parking brake lever takes up space in the operator cab, which reduces the space for other accessories and limits the flexibility of the design.
When parking the vehicle the operator must switch the parking lever to the braking position and when starting the vehicle must release the lever to the release position, which makes the operation troublesome. When temporarily stopping the vehicle on a sloped road, the operator must either use the parking brake or keep the brake pedal depressed to actuate the service brake, which also makes the operation troublesome. If the operator only uses the service brake when temporarily stopped on a sloped road, releasing the brake pedal causes the vehicle to move away from the desired location.
The vehicle disclosed in Japanese Unexamined Patent Publication No. 6-247190 has the auxiliary brake in addition to the service brake. However, the auxiliary brake cannot be used as a parking brake. Thus, when temporarily stopping the vehicle on a sloped road, the operator must keep the brake pedal depressed or use the parking break.